Evaporation apparatus for active ingredients such as pyrethrum incorporated into solid carrier materials

ABSTRACT

In order to improve an apparatus for the evaporation of active ingredients such as pyrethrum or similar insecticides, air-improving, bactericidal, disinfecting and/or, for example, curing substances incorporated in cellular boards or other solid carrier materials, consisting of a housing in which there is provided a heating means which is arranged behind a housing window, and of a holding means for the exchangeable arrangement of an active ingredient carrier panel in front of the housing window in such a way that an evaporation apparatus which is independent from electrical energy can be achieved while maintaining high reliability in handling, it is proposed that a catalytic, merely glowing, that is flamelessly acting burner 4 with fuel tank 3 be arranged in the housing 1 having ventilation openings 13 at such a distance from the housing window 2 that the hot waste gases from the burner 4 flow through the housing window 2 and activate the active ingredients.

The invention is based on an apparatus for the evaporation of activeingredients such as pyrethrum incorporated in cellular panels or othersolid carrier materials, of the type indicated in the preamble to claim1 and known, for example, from DE-OS 3 109 401.

In the apparatus known from DE-OS 3 109 401, there is arranged in thehousing behind the housing window which is designed approximately thesame size as the active ingredient carrier panels, a plate-shapedelectric heating means onto which an active ingredient carrier panel isplaced in order to be heated to about 100° C. in order to evaporateactive ingredients from the heating means.

The electrical heating means is connected inside the housing tooutwardly leading plugs by means of which the device can be connected toan electric supply main.

Evaporation apparatuses of this type therefore invariably require anelectric heating means.

An object of the invention is accordingly to improve an apparatus of thetype indicated in the preamble to claim 1 such that an evaporationapparatus which is independent of electrical energy can be achievedwhile maintaining at least equivalent reliability in handling andrelatively long operating ability as in the past using simple means.

The solution to this problem is characterised in that in the housingcontaining ventilation openings there is arranged a catalytic, merelyglowing, that is flamelessly acting burner with fuel tank at such adistance from the housing window that the hot waste gases from theburner flow through the housing window and activate the activeingredients.

In this way there is obtained an evaporation apparatus which isindependent of power distribution networks with which, on the one handfor activating the active ingredients adequate heating is ensured but,on the other hand, despite the use of combustible substances, the riskof fire and furthermore unintentional contact with the burner are ruledout during operation of the evaporation apparatus.

With this arrangement, it is advantageous if the housing window in thehousing is arranged vertically above the burner and if erection surfacessecuring this position or the like and/or suspension devices areprovided on the housing.

A design which simplifies handling of the apparatus is characterised inthat the burner and the fuel tank are inserted exchangeably into thehousing, the burner and the fuel tank preferably also being combined inone unit.

A further preferred embodiment resides in the fact that the housing, inparticular on the side turned away from the housing window, has anopening through which the burner/fuel tank unit is inserted into thehousing secured at least by friction, the fuel tank preferably beingdesigned so as to seal the housing opening intended for insertion of thefuel tank.

Consequently, the housing can merely be turned over after ignition ofthe burner by means of the burner/fuel tank unit without coming intocontact with the burner, after which a secure connection between theburner/fuel tank unit and the housing is achieved without furthereffort.

For this purpose, an advantageous development is characterised in thatthe fuel tank has a stop which is designed, in particular, in encirclingmanner and in that a groove cooperating with the stop is arranged in thehousing.

A design which improves the effectiveness of the apparatus justdescribed is characterised by a lengthened burner which is arrangedrunning parallel to the base side of the housing on the upper side ofthe fuel tank, furthermore the housing window is oblong in design and isarranged in the same direction as the length of the burner and guideelements which secure this position are provided on the burner tank andon the housing.

In order further to increase the effectiveness, it is advantageous ifthere is arranged, in particular shaped, on the upper side of thehousing an oblong chamber which is smaller than the housing width and isopen towards the burner tank, in whose cover the housing window isprovided, furthermore the oblong burner penetrates into the chamber inthe same direction as the length of the chamber, furthermore in that theventilation openings are provided in the lateral walls of the chamberand that finger-width fuel tank discharge openings are arranged next tothe chamber in the cover of the housing.

A particularly easily ignitable and at the same time manageable designof the subject just described is characterised by a fuel tank which isfilled with liquid fuel, in particular spirit or lighter fuel, in whichmaterial which absorbs the liquid fuel is arranged and at least one fuelvaporisation opening directed towards the catalytic burner is sprovidedin the housing, the fuel tank preferably also having a sealable fillingopening.

In order further to simplify handling, it is advantageous if a burnerignition device is inserted into the housing.

An embodiment of the invention is illustrated in the drawings and isdescribed in more detail below.

FIG. 1 shows an evaporation apparatus for active ingredients embedded insolid carrier materials in section.

FIG. 2 shows the same in the direction of the line II--II, parts of theapparatus being illustrated in elevation.

FIG. 3 shows the same, as viewed from above.

This evaporation apparatus substantially comprises a cylindrical housing1 which is open at the bottom with a housing window 2 arranged at thetop, a fuel tank 3 of flat cylindrical shape and a catalytic oblongburner 4 which is combined to form a unit with the fuel tank 3. The fueltank is inserted together with burner 4 into the housing 1 which is openat the bottom and is secured against unintentional release by acatch-type connection. For this purpose, a raised stop 5 designed as anencircling bead is shaped on the fuel tank 3 and engages detachably intoa groove 6 arranged inside the housing 1. The smooth underside of thefuel tank 3 thus forms with the lower edge portions of the housing 1 thebase for the apparatus. In addition, the housing 1 and the fuel tank 3are designed such that the fuel tank 3 seals the housing 1 which is openat the bottom.

The fuel tank 3 has a filling opening 7 for receiving liquid fuel, inparticular spirit or lighter fuel and is filled with absorbent material8, for example with cotton wool.

A fuel vaporisation opening 9 by means of which the catalytic burner isheld is provided in the upper side of the fuel tank 3. This burner 4consists of an oblong holder 10 composed of porous refractory andgas-permeable material in which solid catalysts, for example finelydivided platinum, is arranged. The ends of the holder 10 are fixed in anoblong sheet metal holder which is fixed undetachably on the fuel tank3.

The oblong burner 4 running parallel to the base side of the apparatusengages in an approximately cuboid chamber 11 which is arranged, inparticular shaped, on the upper side of the housing, is open towards thefuel tank 3 and extends diametrally to the housing 1, the lengthwisedirection of the burner 4 being arranged in the same direction as thelength of the chamber 11.

To permit the prescribed position inevitably to be achieved duringinsertion of the fuel tank 3 together with burner 4 into the housing 1or when turning the housing 1 over the burner/fuel tank unit,orientation means, in particular in the form of straight guide elementsrunning parallel to the axis, can be provided on the housing 1 and onthe fuel tank 3.

To enable the fuel tank 3 together with burner 4 to be releasedconveniently from the housing in an intentional manner for the purposeof filling with fuel and/or for igniting the burner, for example with amatch, a respective finger-sized opening 12 through which the fuel tank3 together with burner 4 can be expelled from the housing by the fingersis provided on the upper side of the housing 1 on the two sides of thechamber 11.

Ventilation openings 13 are provided in the narrow walls of the chamber11. A protective grid 14 and an insertion duct which is open at least atone end for receiving an active ingredient carrier panel 15 inexchangeable fashion is shaped in known manner over the housing window 2of the chamber 11.

If the fuel tank 3 removed from the housing is filled with fuel and theburner 4 is ignited, the housing should be turned by means of theburner/fuel tank unit and only one more active ingredient carrier panelshould be positioned above the housing window.

In order further to simplify handling, an ignition device for example inthe form of a lighter with friction wheel and flint which can beactuated from the exterior or a piezoelectric ignition device can beinserted into the housing above the burner.

The housing 1 together with chamber 11 and holding device for the activeingredient carrier panel is preferably produced integrally from plasticsmaterial while the fuel tank 3 together with burner holder is preferablycomposed of non-combustible material, in particular of sheet metal.

All new individual features and combined features disclosed in thedescription and/or drawings are considered as essential to theinvention.

The burner 4 used in the evaporation apparatus according to theinvention and which can also be described as a catalyst, consists of anapproximately cylindrical holder 10, preferably in the form of a wirenet in which a fleece, preferably glass fibre fleece, is introduced insuch a way that it rests on the interior of the cylindrical wire net.The fleece is thus located in an approximately concentric arrangementrelative to the wire net holder 10 in such a way that the fleece definesan approximately cylindrical cavity. The fleece itself is mixed with acatalytic element, preferably platinum. In this way, the gases issuingfrom the fuel tank 3 enter the interior of the burner 4. The ignition ofthe gases causes the gases in the region of the burner to produce aglowing operation so that no flame is formed at the burner 4 itself andthe heat produced by the glowing of the gases passes directly upwards(FIGS. 1, 2) to the active ingredient carrier panel 15. The heated gasesflow past the active ingredient carrier panel 15 and thus causereinforced volatilization of the active ingredients on the activeingredient carrier panel 15. It is important for the gases produced bythe burner 4 to act directly on the active ingredient holder 15; theactive ingredient panel 15 is preferably arranged at a distance of fromabout 8 to 13 mm from the upper edge of the burner 4.

The evaporation apparatus according to the invention therefore has theobject of conveying the gases issuing from the fuel tank 3 through theburner 4, allowing them to be heated there and of guiding the heatedgases to the active ingredient carrier panel 15 so that the activeingredient carrier panel 15 is heated. To achieve a satisfactory stackeffect, i.e. a flow of the heated gases towards the active ingredientcarrier panel 15 and past it, the width of the housing window 2 (FIG. 1)is selected greater than the width of the active ingredient carrierpanel 15, as shown clearly in FIG. 3, so that the heated gas issueslaterally at the active ingredient carrier panel 15 at the upper side ofthe housing 1. These gases therefore effect not only direct heating ofthe active ingredient carrier panel 15, but also act as a carrier mediumfor the active ingredient particles emitted by the panel 15 owing to theheating thereof. The active ingredient particles are entrained by thegases flowing past the panel 15 and are distributed into the surroundingatmosphere. The supply of oxygen to the burner 4 is ensured by theventilation openings 13 which are formed approximately at the level ofthe openings 12 or by the openings 12 themselves. It is also importantthat the slit-shaped opening formed beneath the burner 4 on the upperside of the fuel tank 3 has approximately the same length and width asthe burner 4 itself or preferably a narrower slit width than the burner4. Part of the burner 4 is a holding member which is composed of metal,is designated by 4a in FIG. 2, surrounds the slit-shaped opening of thefuel tank 3 and holds the holder 10 at a small distance above theslit-shaped opening of the fuel tank 3. This holding member 4a ensuresthat the gases issuing from the opening in the fuel tank 3 pass to theholder 10 and do not escape past the holder 10 into the interior of thehousing 1. The width of the holding element 4a (FIG. 2) is preferablyapproximately equal to the diameter of the holder 10, ensuring optimumsupply of the gaseous fuel from the burner tank 3 to the holder 10.

In order to keep the distance between the burner 4 and the activeingredient carrier 15 in the operating state of the evaporationapparatus within the necessary range, the housing 1 is staggered indesign between the lower portion receiving the fuel tank 3 and the upperportion in which the burner 4 lies, as shown clearly in FIG. 2. Theburner 4 is therefore fixed at a distance from the active ingredientcarrier 15 by arranging the fuel tank 3 on the step (not shown) locatednext to the openings 12.

A further important feature of the evaporation apparatus describedresides in the fact that it is very stable and is substantially securedagainst tilting or accidental tipping over as a result of the relativelylarge, for example circular, standing face. As shown in FIGS. 1 to 3,the standing face is defined in part by the circular lower housingportion and the base of the tank 3.

A continuous and steady flow of hot gases to the active ingredientcarrier panel 15 and past it is produced by the supply of oxygen bymeans of the lower ventilation openings 13 and the slits which aredefined between the active ingredient carrier panel 15 and the upperside of the housing and act as outlet openings. A flow of hot gaseswhich is directed intentionally from bottom (burner) to the top (panel15) and is not impaired by the supply of oxygen from the burner, isobtained, i.e. an accumulation or a vortex and cooling of the hot gasespossibly associated with the vortex is effectively prevented in thespace between the burner 4 and the panel 15.

Finally, the effectiveness during delivery of the active ingredientsduring operation is optimised with the evaporation apparatus accordingto the invention. In addition to the directed steady stream of hotgases, the outwardly or upwardly lying face of the active ingredientpanel 15 is exposed to the exterior with the exception of the negligiblysmall surfaces of the supporting ribs 14, so that the active ingredientsfrom the active ingredient panel 15 are delivered to the environment ina substantially unimpaired manner through housing portions etc.

We claim:
 1. An apparatus for releasing active ingredients in an activeingredient carrier panel by heating the panel, the apparatuscomprising:a housing having a bottom, sides, a top, a housing windowopening to the exterior, means for allowing the entry of combustion airinto the housing, and means for ventilating combustion gas from thehousing exterior through the window opening to the exterior; a heatingmeans including a combustor located within the housing and generallybeneath the housing window opening; the bottom of the housing having anopening through which the heating means can be inserted into thehousing; means for frictionally securing the catalytic heating means tothe housing; an active ingredient carrier panel having a surface arealess than the surface area of the housing window; and means forreplaceably positioning the active ingredient carrier panel above theheating means and across the housing window opening; whereby heated gasgenerated by the heating means rises within the housing, passes throughthe housing window and is caused by the shape of the housing to impingeupon the active ingredient carrier panel to thereby heat and release theactive ingredients and carry them with the heated gas to the exterior ofthe housing.
 2. The apparatus of claim 1 wherein the panel is disposedexteriorly of the window opening, and including a protective gridextending over the panel and an insertion duct for the panel defined bythe housing.
 3. The apparatus of claim 1 wherein the heating meanscomprise a burner and a fuel tank adapted to be exchangeably insertedtogether into the base of the housing.
 4. The apparatus of claim 1wherein the heating means includes a tank and a burner in fluidcommunication with the tank, and wherein the housing is tapered at itstop and sides to form a chamber of reduced cross section adapted toaccommodate the burner.
 5. The apparatus of claim 1 wherein the heatingmeans comprises a burner and a fuel tank combined to form one unit. 6.The apparatus of claim 5 wherein the fuel tank is shaped to effectivelyclose and seal the opening in the bottom of the housing.
 7. Theapparatus of claim 5 wherein a bottom surface of the fuel tank forms asupport surface for the housing.
 8. The apparatus of claim 5 furthercomprising a burner ignition device extending into the housing. 9.Apparatus for releasing active ingredients in an active ingredientcarrier panel by subjecting the panel to an elevated temperature, theapparatus comprising:a housing defined by a downwardly open base of agiven cross section and a top of a relatively lesser cross section influid communication with an interior of the base and including a windowadjacent an upper portion of the top which communicates the interior ofthe top with the exterior of the housing; means connected with thehousing for replaceably positioning the carrier panel across the windowso as to provide space for flowing hot gas from the interior of thehousing about a periphery of the panel and through the window to theexterior of the housing; catalytic heating means including a fuel tankadapted to be located interiorly of the base and a catalytic burner influid communication with the tank through which fuel vapors can pass,the burner being positioned in the interior of the top and generallybeneath the window opening so that gas heated thereby flows towards aside of the carrier panel facing the housing interior and hence aboutthe periphery of the panel to the exterior of the housing; snap-on meansdefined by the housing and the catalytic heating means for releasablyretaining the tank interiorly of the base so that the burner isproximate the interior of the top; the housing defining air inletapertures proximate the burner to sustain a catalytic combustion of thefuel;and cutouts in the base positioned to provide finger access to thetank for manually forcing the tank and thereby the heating means out ofthe housing to facilitate the replacement of the heating means.